This invention relates generally to the automotive industry and more particularly to repairs of vehicles.
A major problem in the auto-body repair industry is referred to as "spring-back". This is a condition caused by stress in a damaged section of a vehicle which results in the metal springing back a considerable distance when the pulling device is released. To overcome this condition, the technician must stress relieve the structure.
Traditionally there have been three basic ways used to stress relieve metal.
(1) Heating by torch: This method is no longer allowed as it damages modern sheet metal alloys by altering the molecular structure; PA1 (2) Hammer: By far, this is the best available method, but has definite limitations due to restricted space in most situations. Hammering can also cause secondary damage. PA1 (3) Over-pulling: This is done with the hope that the metal springs back to the correct dimensions. PA1 (a) Pull is too light: In this case the damage springs back too far and the task requires additional pulls and wasted time; PA1 (b) Pull is too heavy: When this occurs, the damage doesn't spring back far enough.
With over-pulling, there are usually two results:
Further, when the pull is too heavy, a variety of ancillary problems develop. Even if the metal does not tear, the result may be that the metal may row have more damage than presented initially. To correct, the section must now be re-dimensioned, and/or crush-control sections must be restored. This is very time consuming and an expensive procedures (i.e. Metal shrinking, section replacement, etc.).
Because of this, most technicians will err on the side of a pull that's too light.
It is clear that there is a significant need for a tool which will assist in proper correction of automobile damage.